Old Enemies
by ButternutSquash112
Summary: What would have happened when an old enemy of Percy's comes back to play?
1. Chapter 1

Leo leaned far out over the edge of the Argo II and spit out as far as he could. A wad of saliva flew through the air and landed with a splash in the ocean over ten meters from the ship. Jason, who stood beside Leo, cheered over this great victory and clapped Leo on the back. The boys were so involved in their game that they didn't notice the two figures shaking their heads at them from across the deck.

Hazel and Piper watched, unimpressed, as the boys spit farther and farther out over the edge. Eventually, they turned away from the pair and continued the conversation they'd been having before.  
"She was the only person he remembered, even when the rest of his memory's were all gone!" Hazel squealed to Piper.  
"She never gave up looking for him, even after he'd been gone eight months!" Piper returned in the same high-pitched tone. As is obvious, Piper and Hazel were gossiping over the love story of Percy and Annabeth, who had been together longer than anyone else aboard the ship.

Down below decks, Coach Hedge lounged in an overstuffed recliner armchair. His hand was stuck in a bowl of popcorn and his small eyes focused on the illuminated T.V. screen. He was shouting at the people in the television, and these shouts could be heard echoing all throughout the lower decks of the ship.

In another room, Frank, Annabeth, and Percy were seated around the table in the lounge. The conversation held between the three of them was of a much more serious matter.

"I'm not sure he can be trusted. I saw him at dinner... he looked like a zombie." Annabeth said in a hushed tone.

"I don't really know the guy, but he seems like the kind of person you could trust. I don't think he was acting of his own free will," Percy said, continuing the trio's conversation of Leo's firing on New Rome.

"I don't like him. But even so, he doesn't seem like the type to attack. He just doesn't seem that serious," Frank said quickly.

"So we're in agreement. Something forced Leo to fire on New Rome. Something, or someone, wants war between the Greeks and Romans and they've got powerful enough magic to possess a person and control them to act completely against their will." Annabeth said firmly.

"Could it be Gaea? She's been growing more and more powerful of late. She could have some mind-possessing demon or whatever that could have gotten to Leo." Percy said questioningly.

The trio continued their serious conversation in hushed tones, as Leo and Jason continued their competition, Hazel and Piper their gossiping, and Coach Hedge watching fencing competitions in his room.

None of them were aware of of a ninth passenger aboard the ship. None were aware of it's evil lurking presence, and none of them would have ever guessed that it could have ever possibly existed again.


	2. Chapter 2

**AN: Thank you guys for reviewing and for the great advice! XD Keep reviewing! (It makes me feel all special inside)**

Standing stock still at the rear end of the ship was a tall, slim figure. Sunlight glinted off of the mysterious visitor's hair, and this new arrival radiated an essence of evil. Evil so ancient that not many that knew it still walked the earth today. Gripped in the figure's hand was a long, wicked blade, sharp enough to cut a man's head from his shoulders with one solid swing. The person listened to an argument the rang through the air, echoing from the front of the ship.  
"I told you! We. Do. Not. Play. With. Fire. Around. ME!" shrieked Hazel, panicking as bursts from Leo's hands danced around.  
"Awww, come on Hazel. It's just a bit of fun!" Leo complained in a slightly nasally, quite nasty voice.  
"Cut it out!" Piper cried, noting the look of horror on her best friend's face.  
"Dude.." Jason murmured into Leo's ear. "Come on, quit it."  
Leo sighed and lowered his smoking hands to his sides. Something flashed through his eyes, and he gave Hazel a wicked grin and winked at her before dashing below decks.  
"What was that all about?" Piper asked nervously, putting a comforting arm around Hazel.  
"No idea." Jason said, slightly disgruntled. "Leo's been acting weird ever since that incident back in New Rome. He's probably just a little shaken up. But still..." he trailed off, looking slightly confused as to why his best friend would pull such a risky prank.  
The sound of feet pounded up the stairway, just before Percy and Annabeth rushed through the door.  
"Where's Leo?" Annabeth instantly, looking around the deck to see if Leo could be hiding around a corner or behind a wall.  
"He just ran downstairs," Jason responded, "he was shooting fire at Hazel. We're pretty sure somethings wrong with him."  
"We're sure there's something wrong with him," Percy replied. "We've been talking it over downstairs, and we're pretty sure we've figured out what's wrong with him."  
"Right," said Annabeth, "we already know that Leo's not himself. What we don't know is what could be making Leo act so differently than normal. We're suspecting Gaea, because she seems to be the cause of everything these days. We also have a couple theories as to how Gaea can be controlling Leo from so far away."  
"Yeah," Percy continued, "we IM'd Chiron to catch him up on some news and asked him about possessing spirits. It isn't pretty. We're pretty sure that an Eidolan has got hold of him, but we're not sure what it could make him do, or how to get rid of."  
"Which means," Annabeth broke in, "that we need to keep a close eye on him for the time being. So where is he?"  
"Like we said, he's downstairs," said Piper, "but where's Frank? Wasn't he with you guys?"  
"He was right behind us..." Percy muttered.  
"Where could he have gotten too?" Annabeth said, "we've got to go find him. With Leo in the state he's in, it's probably best to stay in pairs. We don't know what he's capable of. Come on!"  
Annabeth dashed back through the open doorway with Percy, Hazel, Piper, and Jason on her heels. They dashed through the bottom decks of the Argo II before finally finding Frank standing alone in the stables.  
Frank stood with his back to them, strangely still and unresponsive when they called his name. Slowly, he turned around, with a smile nearly identical to the one Leo had flashed to Hazel right before he dashed away.  
"Frank's not here right now," he said slowly, in a slightly slurred way. "Can I take a message?" He stood stock still as Hazel let out a small whimper.  
He fixed his eyes onto her and a sadistic light poured into them. Then, he disappeared into thin air.


	3. Chapter 3

The instant Frank vanished from before their eyes, all hell broke loose. Hazel screamed, Percy leaped forward trying to grab Frank, Annabeth looked around for some trace of magic or hidden door that Frank could have used to escape, Piper grabbed onto Jason, and Jason noticed a small figure lying limply in a corner.

Jason leaped away from the group of terrified people and rolled over the limp body of Leo Valdez. His eyes were half-shut and his skin was a death white. His curly hair stuck to his head and a low moan escaped his mouth.

Percy rushed over to the two boys, and the two worked together to lift Leo up and carry him to the infirmary, where Piper was already waiting with some Ambrosia and Nectar. Fever was coursing through Leo's body, and the ridiculous amount of ambrosia that Piper was trying to feed to him was not helping.

Just then, Hazel walked through the door of the ship's infirmary, looking like she was about to have a panic attack. "Guys?" she asked in a quiet tone, "where did Frank go?"

"Umm.." Percy started, unsure as to where to begin, "let's go for a walk, okay?"

Percy and Hazel were standing towards the front of the ship. Percy slowly turned and faced Hazel, not wanting to tell her what he was sure had happened to Frank.

"Hazel.." he began. "Do you remember when Leo was acting weird? Like something was possessing him?"

Slowly, Hazel nodded.

"Well, we think that whatever was wrong with him may have been passed on to Frank. But it was strong then, or it affected him more greatly. Whatever it was, whoever was in control of that possessing spirit took Frank."

Hazel gasped. "Was it Gaea? Is she the one that has him?"

Slowly, Percy nodded. "Yeah," he said. "That's what it looks like."

Hazel stood quietly for a moment, then burst into tears. Percy put his arms around her as she sobbed. After a few minutes, she wiped her eyes and looked up Percy with a brave and determined expression on her face.

"Well then. I guess we're just going to have to go get him back." Percy smiled and nodded and walked with Hazel back downstairs.

Back downstairs, Leo's condition had not changed. The coach had tried his nature magic, and Piper had already used too much Godly food to be considered safe. They'd done all the could, and now they'd just have to sit and wait.

"So maybe we should try and figure out what actually happened," Jason begun, trying to sound leaderly and in charge, seeing as Percy wasn't there. "Whatever Leo had was probably passed off to Frank, so Leo would be back to normal now, right?"

"Seems about right." Piper responded, "But why I don't get is why the spirit, or whoevers controlling it, didn't take Leo. Why did it take Frank instead, out of all of us? If they wanted to throw the group into discord, why not take Percy? He's the real leader of this quest. Without him, we wouldn't even know how to start."

Jason, who looked rather annoyed at the praise being delivered to Percy, responded, "Hey, Frank's a great guy. We need him. Don't underestimate him."

"But still..." Piper began, but Jason shot his girlfriend and angry look before leaving the room.

Leo looked around in confusion at the pristine white walls and sparse furniture. He turned all the way around the room before noticing Frank Zhang sitting in a corner.

"Um, what's going on?" Leo asked in a confused and questioning manner.

"You expect me to know? I've been here even less time than you have," Frank responded.

"I was spitting with Jason over the edge of the ship... but now I'm here. Did I lean out too far?! Am I dead?!" Leo cried.

"No! You're not dead. Is that when it got you though? Right after you were spitting?" Frank questioned.

"Yeah, of course. Well, actually, no. No. I've been here once before, but I couldn't remember it. When we were at New Rome, and I was with Octavian on the ship. That's when I fired on the city right? That wasn't my fault, you know, I didn't do it!" Leo said with a panicky voice.

"It's okay I believe you. I wasn't there, but I think you did something pretty bad after the spitting contest. I heard a lot of screams from the deck, and the sound of fire. And then you came and found me in the stable and looked at me in a really funny way. Then I showed up here," Frank finished rather unimpressively.

"Oh, God. Oh, God. Oh, God," Leo muttered under his breath. "What did I do? Is everyone okay? My ship... is it safe?"

Frank rolled his eyes. "Yes your boat is quite safe. And I don't know what happened, I'm here too. In case you have noticed. By the way, do you think you could fix whatever's wrong with you? It's really kind of creepy."

"Huh?" Leo asked in confusion, "What's wrong with me?" Just then, Leo looked down and saw that his entire body was transparent, and occasionally flickering. "WHAT? Why do I look like this?

"No idea," Frank said. "Want me to guess? I'd say it's probably because you're not possessed anymore, you gave that curse to me. You just haven't left this place yet."

"Oh... right..." Leo trailed off. Continuing to look at his arm as it grew fainter and fainter.

"Listen, before you go," Frank said suddenly, "tell... tell Hazel I'm okay, will you? I'll be okay."

"Yeah, of course, man. Don't worry, we'll all take care of her," Leo promised. Frank gave him one last small smile before disappearing completely.

In the Argo II infirmary, Leo Valdez woke with start. The darkened room was empty, and Leo had the feeling that a great deal of time had passed. Leo blinked rapidly, trying desperately to remember the memory of his and Frank's conversation in that strange white room. As Leo sat with his head buried in his hands, the door behind him slowly creaked open and Hazel and Percy walked into the room. Percy stopped as soon as he saw Leo's upright position.

"Hey! You're up!" Percy began, as if not sure what to say, "how're you feeling?" Hazel hung nervously back at the door, not sure whether or not Leo was back to his normal self.

"Um," Leo began hesitantly, "Yeah, fine. Listen, Hazel, I was talking to Frank a minute ago and he said... he said not to worry. That he'd be okay."

Hazel nodded, her eyes sparkling with unshed tears. Leo tried and failed to send a small smile in her direction, but his attempt went unnoticed, as Hazel had already turned and slipped out of the room.

"So... um." Percy began as he stood awkwardly just inside the doorway, "So, do you remember anything. From, like, recently?"

Leo smirked as Percy shifted his weight and nervously ruffled his hair. "No. Franks was saying something about fire?"

Percy proceeded to explain all that happened aboard the Argo II from the fire incident to Frank's disappearance. Leo listened carefully to every word and looked surprised when Percy described Frank's sudden vanishing.

Leo nodded, gazing at the floor as he tried to figure out just what had happened to him and Frank. Percy quietly said his goodbyes and left, leaving Leo alone to his thoughts. He fell asleep at some point over the next hour, and only woke to a hand pressing a cloth over his mouth and vicious, gleaming blue eyes glinting at him from out of the darkness.


	4. Chapter 4

Percy was walking down the corridor back to his room, shaking his head as he thought about the recent happenings. Percy wasn't sure if whatever had gotten Leo the first time would come back, or if it were gone for good. Percy wasn't even sure if Leo's innocent, I-remember-nothing act was just that, an act. How could they be sure he wasn't waiting, ready to destroy the ship when no one was awake, or slit somebody's throat as they slept. But he wouldn't dare voice his concerns to anyone else. Coach Hedge would throw the boy behind bars without blinking an eye. Percy didn't want to lock up a perfectly innocent, already terrified little kid.  
He was so lost in his thought that he didn't hear the footsteps coming up behind him until it was almost too late. A gentle pad, pad, pad came from behind him. Percy stiffened, his hand instinctively going to his pocket. He wrapped his fingers around the pen's smooth surface, and in one fluid motion, he pulled Anaklusmos from his pocket, ripped the cap off and pointed the full-sized, glowing blade at his attacker's throat. Shadows covered the figure's face, making it impossible to make out who it was. What dim light there was gleaned off of the intruder's teeth, and a smile sprouted from the darkness like the Cheshire cat.  
A blade suddenly swooped from the blackness and shoved away Percy's with such an ease that only years of training could deliver. Percy countered and soon realized how badly at a disadvantage he was. He couldn't see any movements from his assailant, whereas the attacker could see every inch of him. Ducking quickly around the figure, Percy slipped into the same darkness as the intruder. It was then that he realized that even on a fair playing field, Percy would not be able to beat this man, whomever he was. His blade was longer and heavier than Riptide, and he could wield faster and with more precision than Percy had ever been able too. Knowing that in order to win this battle, Percy had to have some advantage, he decided to go on full offense as he tried to push the intruder into the strip of light Percy had been standing in earlier. But these attacking movements only left Percy undefended, and he was quickly disarmed and knocked to the floor.  
Percy scrambled backward, feeling for his blade, as his assailant approached him on quiet, measured steps. The last thing  
"Hey there, Percy," whispered a quiet, yet familiar voice. "Miss me?"  
And then a blow to the head dissolved the world into blackness.

Annabeth lay flopped in her bed, tangled up in sheets and the power cord to her laptop. She rubbed her eyes as she pushed herself up into a sitting position. She opened the lid of the computer and continued working on the plans she had fallen asleep with last night. She had been focusing on the glowing screen for fifteen minutes before a frantic banging rattled her door. Jumping in surprise, she threw off her sheets and rushed to open the door, revealing a panicked and flushed-looking Piper.  
"Come quick," she panted. "Trouble." Annabeth and Piper rushed to the infirmary to find Jason, Hazel and Coach Hedge already kneeling beside Leo's bed, looking perfectly healthy, to Annabeth's' relief. Leo, on the other hand, lay sweating and panting, his eyes rolling upward in his head. His hands twitched on the sheets and his legs kicked anything within two feet of them. His spine arched and relaxed, over and over again. Suddenly, one of Leo's hands flew from the bed clothes and smashed into Jason's head. Gasping in surprise, Jason quickly rebounded as Leo's hands flew to his own throat. Jason prevented Leo from strangling himself as Annabeth rushed to the medicine cabinet where she gathered everything she needed to break a spell. She knew a curse when she saw one.  
Once Coach Hedge and Piper calmed down, they began to help Annabeth in her treatment of Leo, as Jason continued to hold him down. After five stressful minutes of hard work, Leo sighed in his sleep and relaxed. Jason sat back and, wiping sweat from his forehead, turned to Annabeth and the others,  
"Okay so... what exactly happened here? Somebody poisoned Leo, I got that. But who would have done it?"  
"I have no idea," Annabeth said, sighing. "But if I had to guess, I would say that posessing spirit came back and either made Leo poison himself or made one of us poison him. We wouldn't even remember it." Hazel paled at the thought that she could've been the one to do this to Leo. Everybody went quiet for a few minutes, thinking about what had just happened.  
Suddenly, Jason looked up again, just as confused as the first time. "Hey, Piper? Where's Percy? Did you go to get him?"  
"Yeah, I knocked on his door but he didn't respond. I just assumed he was still sleeping."  
Annabeth smirked, "Bet he was. But we'd better go and wake him up so he's knows what's been going on."  
"Yeah," Jason muttered, before standing up and following Annabeth through the infirmary door with the Piper and Hazel trailing behind. Coach Hedge stayed by Leo's side with his feet kicked up on one of the near-by beds.  
The group walked through the corrider to Percy's room in silence. Without bothering to knock, Annabeth opened the bed room door, took a step inside, and froze. Hazel bumped into her because of the sudden stop, buut Annabeth didn't move. Percy's bed was perfectly made, there was no way he could have slept there the previous night. Either he had wandered the ship all night long, or he wasn't even on the ship at all, anymore.  
"Hazel," Annabeth said, turning, "Last night when you and Percy were talking to Leo, what happened?"  
Blinking, Hazel replied hesitantly, "Well.. Leo was awake. He told me Frank was okay. Then Percy started talking to Leo about everything that had happened and I left."  
"So the only person who would know would be Leo?" Hazel nodded. "Great. Just great."  
Annabeth walked briskly from the room and back to the infirmary where she found Leo, who was just beginning to stir.  
"Wakey, wakey, eggs and bac-y." She muttered to Leo as he slowly drifted awake.  
As soon as Leo's eyes were fully open, the interrogation begun.  
"What happened?"  
"Uhhh... I'm not sure."  
"Who did this?"  
"No idea. Couldn't see in the dark."  
"Where's Percy?"  
"Is he missing?"  
Annabeth growled in frustration at the lack of progress. She was about to start back up Leo's interrogation when Piper cried, "wait!" She then whipped Katoptris out of her belt and focused intently on the reflection.  
"I know where they are." She cried after a minute. "Frank and Percy, I know where they are!"


End file.
